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Another observation,
At full reflex, the wing center of pressure moves
forward,
efectively moving the CG further to
the rear,
requiring more down elevator,
possibly creating negative stability
(depending on your CG to start with).
So . . . if you load with a further forward CG
with the above in mind, (trim for fast cruise),
you end up with a condition where you
do not have enough elevator for a slow, full flap, full flair
landing.
Leading me to conclude that the LNC2 does not have
enough elevator authority.
Needs more elevator area (the kangaroo
tail) or a tail further back.
. . . if you want to keep a usable 6"
CG range . . .
Wolfgang
----- Original Message -----
Sent: Sunday, September 29, 2013 10:53
PM
Subject: Re: [LML] Re: Lancair 320/360
performance and stability
So I happened to be looking for something unrelated in the FB manual and
came across this on page 10-24:
"Lancair flaps are full electric actuated. They are designed to run
from +45 down to -10 up (reflex). Note that the 'faired in position' for
flaps is actually a -7 deg reflex position. ....."
My standard build manual is in storage so I could not compare. It
would appear the intent was to be able to go to -10 degrees after all.
Chris Zavatson
N91CZ
360std
From: Christian Meier
<lancair@meier.cc>
To:
lml@lancaironline.net
Sent:
Tuesday, September 24, 2013 3:19 AM
Subject: [LML] Re: Lancair 320/360
performance and stability
Chris,
today I made a picture during Cruise with Autopilot at 7500ft with
following configuration:
770 kg 40l in header, 20l in each wing (80l total), 75kg and 83kg
for pilot and co.
Flap was on 7° reflex CG 26,20"
My design CG is 22,8 - 30,3 from firewall back,
horizontal was installed - 0.6°
So it looks like if I would add more reflex than 7°, I would need more
down elevator.
So the gain with the higher reflex would be lost with the down
elevator....
Christian
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